One such type of heat exchanger often is used to heat consumable water and heating water in living units, with the heat energy being supplied from a remote heating system. The heat carrying fluid, most often hot water, delivered by the heating system flows through the primary-side flow path and in doing so transfers heat to the consumble water or to the heating fluid which flows through the secondary-side flow path. As a rule, the fluids flowing through the primary-side flow path and the secondary-side flow path flow in opposite directions, so that the water of the secondary side can be heated to a temperature higher than the temperature of the fluid at the downstream connector of the primary side.
To maintain a quite exact temperature adjustment at the outflow connector, the flow of the heat carrying fluid of the primary side is controlled in dependence on the heat given off by the secondary side. This will be explained below by way of example, in which consumable water is heated in the heat exchanger. As soon as consumable water is taken from the outflow connector of the secondary side, cold consumable water flows into the inflow connector. Accordingly, at almost the same time, heat carrying fluid must be able to flow through the primary-side flow path so that sufficient heat can be transferred to the secondary side.
In order to control or regulate a valve so that the fluid flow of the primary side is controlled, frequently a temperature sensor is used to regulate the valve.